Adjustable, hand held wrenches are available in a variety of sizes and designs and are well known both to those skilled in the art and to the layman. One of the most commonly used of such wrenches is the two surface adjustable wrench, including the so-called crescent wrench. Examples of various types of two surface adjustable wrenches are described in the following U.S. Pat. Nos.: 1,127,100; 2,018,047; 3,198,041; 3,659,485; 3,563,118; 3,599,516; 3,802,303; 4,011,778; 391,532; and 784,876. The two surface adjustable wrench, however, has a number of drawbacks which render it awkward to use and which often preclude its use in certain situations. One drawback is that it is often impossible in blind situations to determine which direction the wrench adjustment screw must be rotated to either open or close the wrench jaws. Another drawback is that the wrench has a preferred direction of rotation under high torque applications to obtain the optimal coupling action between the nut or bolthead and the wrench, and space limitations often prevent the wrench from being used in its preferred direction. The major limitation of such a wrench is its inability to remove nuts or boltheads under high torque conditions. This limitation is partially a result of the fact that a two surface adjustable wrench applies torque to the nut or bolthead at only two points. In addition, as a result of many factors such as slippage of the adjustment, the spring characteristics of the jaws, burrs and so forth on either the faces of the jaws or on the nut, and dirt or grease on the wrench head faces or nut faces, the actual moment arms are reduced from a maximum value to a smaller value because of rotation of the wrench head with respect to the nut. To apply a given torque, an increased force must be applied to the corners of the nut because of the reduction of the moment arm. This increased force is often sufficient to begin a rounding off of the corners which often produces an angle of the wrench handle with respect to the nut which reduces the moment arm even more. Often, this process degenerates to the point where the wrench will no longer grip the nut and damage to the user's hand can result. In addition, because of the two point contact and rotation of the wrench head with respect to the nut, the wrench head must be capable of withstanding great forces in high torque situations, and this necessitates thick wrench head walls. These thick walls render the wrench very difficult to maneuver and use in limited space applications.
Some of these disadvantages of the crescent wrench have been overcome by known self-camming wrenches, or wrenches having pivotally disposed wrench heads. Examples of such wrenches are described in U.S. Pat. Nos.: 2,506,373; 3,023,652; 909,101; 1,380,822; 282,768; 453,537; 1,436,698; Danish Pat. No. 69,620; German Pat. No. 1,958,614 and British Pat. No. 5,196. Many of the above self-camming wrenches are not suitable for hexagonal nuts or boltheads and do not provide a desired offset of the wrench head with respect to the handle. In many of the known self-camming wrenches, particularly the wrench disclosed in the German patent, when the handle is pivoted with respect to the wrenchhead, the camming surface on the handle engages a nut face at the center thereof and provides a force which is directed towards the center of the nut and which drives the nut against opposed walls of the wrenchhead. This inwardly directed force force provides no torque with regard to the nut and tends to deform either the nut or the wrenchhead. The only turning moments acting upon the nut result from forces acting upon the corners of the nut by the opposed walls of the wrenchhead. In addition, this great inwardly directed force necessitates an excessively strong wrenchhead, because of the counterforce which must be applied by the opposed walls of the wrench head. Thus, as with the two surface adjustable wrench, the required thick walls of the wrench head render the wrench very difficult to maneuver and use in limited space applications. Many of these wrenches, particularly the wrench disclosed in the German patent and that found in U.S. Pat. No. 3,023,652 are not bidirectional. Such unidirectional wrenches are awkward to use and must be raised from the nut and inverted before the direction of rotation can be reversed, and in confined areas, it is often difficult to determine whether the wrench is properly oriented with respect to the nut to rotate it in the direction desired. Also, in the unidirectional wrenches, it is only possible to detent the position of the wrench by increments equal to the angular separation of each nut face.
Examples of wrenches and the like having enclosed, non-pivotally attached wrenchheads and a movable jaw for adjusting the size of the wrenchhead opening are disclosed in U.S. Pat. Nos. 2,506,373 and 2,748,640. While such wrenches overcome some of the problems of the crescent wrench and the self-camming wrenches, they provide no means for insuring that the nut or bolthead is secured within the wrenchhead during movement and they provide no offset to the handle.